This invention relates generally to automated mail sorting equipment and deals more particularly with an improved mechanism for feeding envelopes in a high speed mail sorting machine.
High speed mail sorting equipment is used by various businesses, institutions and governmental units that are faced with handling large volumes of mail. For example, banks, credit card companies, utilities, advertisers and mail order businesses send and receive huge amounts of mail each day. Outgoing mail is typically sorted by zip code prior to mailing. Incoming mail is usually sorted prior to being routed to the proper department.
In order to efficiently sort large volumes of mail, various types of automated, high speed mail sorting machines have been proposed, as exemplified by the machine shown in U.S. Pat. No. 4,275,875 which issued to Roy Akers on June 30, 1981 and assigned to the assignee of the present application. In this type of equipment, the envelopes which are to be sorted are loaded in a stack onto a magazine section of the machine. An envelope feeding mechanism delivers the envelope to vacuum belts which pick the envelopes off one at a time from the envelope supply. The envelopes are thereafter handled individually, and each envelope is conveyed past a reading station at which its zip code or another code imprinted on the envelope is read, either by an operator of the machine or by a code reading device. Envelopes having the same or a similar code are directed into the same storage bins to complete the mail sorting operation.
Although this type of machine has functioned well for the most part, it has not been wholly without problems. A particularly difficult problem has been encountered in providing a reliable arrangement for separating the individual envelopes from the stack in the magazine section of the machine. Vacuum pick off systems have been generally satisfactory, but they rely on proper feeding of the envelopes in order to separate the individual envelopes from the stack one at a time. If the envelopes are bunched tightly together as they approach the vacuum belt, there is a tendency for the envelopes to stick together, and more than one envelope at a time is picked off. Similar problems result if the envelopes are skewed or otherwise improperly positioned as they are fed against the vacuum belts by the feeding mechanism.
It is thus apparent that the pick off device can perform its function properly only if the envelopes are fed to it in the proper manner. Consequently, an effective envelope feeding mechanism is necessary in order for the mail sorting machine to sort the envelopes in a reliable fashion.
The present invention is directed to an improved envelope feeding mechanism for feeding envelopes to a pick off device in a high speed, automated mail sorting machine. It is the principal object of the invention to provide an envelope feeding mechanism which maintains the envelope supply in a relatively loose condition as the envelopes are fed to a pick off device such as a vacuum belt system. Another object of the invention is to provide an envelope feeding mechanism which maintains the envelopes in an upright and non-skewed posture as they are feed to the pick off device.
In accordance with the invention, the magazine section of a mail sorting machine has a floor surface which receives a supply of incoming envelopes with the lower edges of the envelopes resting on the floor. The floor is inclined from side to side, and the side edges of the envelopes rest against an inclined side plate extending along one side of the floor. A drive chain travels along the side plate and has projecting lugs which convey the envelopes along the length of the inclined floor.
At the discharge end of the floor, the envelopes are deposited onto a conveyor belt which is driven in a direction perpendicular to the direction of travel of the envelopes along the magazine floor. The conveyor belt delivers the envelopes to a driven roller having a spiral groove which feeds the envelopes one at a time to the pick off belts. A second grooved roller is elevated to receive the leading edge of each envelope, thereby maintaining the envelopes vertical and square with the vacuum belts against which they are fed.
It is a particularly important feature of the invention that the conveyor belt is driven at a faster speed than the drive chain. The faster speed of the conveyor belt causes the envelopes to spread out as they travel downstream toward the pick off device. Consequently, there is a reduction in the tendency for the envelopes to be tightly bunched together as they approach the pick off device. The relatively loose condition of the envelopes at the time they encounter the vacuum belts reduces multiple envelope picking and other picking problems, thereby enhancing the overall effectiveness and reliability of the mail sorting operation.